Transportation Systems and Materials

Research Project Abstracts: 2002 - 2003

An Estimate of the Visibility of Signs Installed on the Roadside Using Videologs
J. E. Hummer
3M Company
07/02 to 12/02
3M designs sign sheetings that may be viewed by a driver with no sight obstructions from a long distance. Once signs are placed on the roadside, however, any number of obstructions may block the line of sight from a driver to a sign. Some of these obstructions include trees, hillsides, hillcrests, walls, and other signs. On many U.S. highways, these obstructions may essentially negate the capabilities of the sheeting. The purpose of this project is to determine, for a representative sample of U.S. highways, the distances at which installed signs become visible to the driver.

False Capacity for Lane Drops
J. E. Hummer and N.M. Rouphail
NC Department of Transportation
07/02 to 06/04
The purpose of this study is to collect operational and safety-related data at intersection approaches that have downstream lane drops. The data will be used to develop a lane utilization prediction model, which will take into account, among other things, the design features of the downstream lane drop. This model is critical in estimating capacity and level of service for the intersection approach. The safety data will identify those lane design aspects that appear to promote safety and provide a smoother merging process.

Effects of Increased U-Turns at Intersections on Divided Facilities and Median Divided Versus Five-Lane Univided Benefits
J. E. Hummer, J.S. Milazzo II and R.S. Foyle
NC Department of Transportation
07/02 to 06/04
The purpose of this project is to provide the best possible information on the rival cross-sections. The project team will calibrate a collision model for each type of cross-section. This collision model will include terms for driveway densities and other factors, which will allow the model to make much more credible predictions about the safety of future roads than can be made currently using collision rates. The project team will also collect operational and safety data at intersections on four-lane divided cross-sections where significant volumes of u-turns are present to see whether those u-turns cause the problems attributed to them.

Railroad Crossing Wayside Horn Evaluation
J. E. Hummer
NC Department of Transportation
07/02 to 06/04
The noise from train horns is irritating to people living and working along railroad tracks, and causes opposition when new train service is proposed. However, the train horn is also an essential safety device for motorists at grade crossings. A device called a wayside horn has been marketed in the U.S. that promises to reduce that irritation by mounting the horn at the road crossing and directing the sound at motorists. The purpose of this project is to evaluate the device at two crossings in North Carolina by means of driver surveys, resident surveys, and roadway operational measures.

Evaluation of Safety, Design, and Operation of Shared Use Paths
J. E. Hummer, N. M. Rouphail, and J. S. Milazzo II
Federal Highway Administration
10/00 to 09/03
Off-street paths used by pedestrians, bicyclists, and other non-motorized users are becoming common in the U.S. To provide better and more cost-effective facilities, designers and operators need guidance on the quality of service offered by paths of different widths and configurations handling different volumes of users. The purpose of the project is to develop and validate a quantitative procedure for estimating that quality of service. This research builds upon a methodology recommended by the research team in a previous project for the Federal Highway Administration. A major work element in this research is the collection of operational data on paths across the U.S. The research team will also collect an extensive database of path user perceptions. Another important part of the research is the development of a plan to communicate the quality of service procedure to designers and operators across the U.S.

Communicating Changes in Horizontal Alignment
J. E. Hummer
Michigan State University
08/01 to 08/03
Working as a subcontractor on National Cooperative Highway Research Program Project 3-61, we are investigating ways to more effectively and consistently warn drivers about upcoming horizontal curves. We are gathering information about current curve warning devices and methods through a literature review and a series of surveys. We will then be developing new methods and devices. Our primary role at NC State is to test existing and new methods and devices at sites on North Carolina highways.

Determination of Optimum Gradation for Resistance to Permeability, Rutting and Fatigue Cracking
N.P.Khosla
NCDOT/FHWA
07/02 to 06/04
With the new Superpave mix design system in use today, more and more coarse graded mix designs are being used. With these coarse graded mixes, there are more interconnected voids in the pavement layers, causing higher permeability. These permeable pavements allow water to pass through them and cause premature failures. Thus, it is important that the gradations be developed for surface course mixtures, which are coarser in nature with fewer interconnected voids so that their performance is not affected by the moisture damage. The Bailey method is proposed to be used for analyzing the packing characteristics of a blend of aggregates. The Bailey method of Gradation Analysis presents the foundation for comprehensive gradation evaluation and modification procedure. It outlines a method to combine aggregates that provide aggregate interlock ad the backbone for the aggregate skeleton. Aggregate ratios, which are based on particle packing principles, are used to analyze the particle packing of the overall aggregate structure. This study will provide a sound methodology of modifying surface course mixture gradations to yield low permeability and superior performance. A band of gradations will be recommended meeting the criteria of low permeability and superior performance. In order to ensure quality performance of pavements, the mixtures made with modified gradations and having low permeability will be evaluated in terms of their resistance to rutting and fatigue cracking using Simple Shear Tester and Asphalt Pavement Analyzer.

Determination of Dynamic Moduli for Typical North Carolina Asphalt Mixtures Modified with Lime
Y. R. Kim
Chemical Lime Company
05/03 to 05/04
The objective of this proposal is to develop a dynamic modulus database for typical asphalt mixtures modified with lime in parallel with the NCDOT database. Only the axial compression test method will be used in this project with the anticipation of adding the indirect tension test method later when funds are avaiable. Also, the applicability of Witczak's predictive equation to lime-modified mixtures will be evaluated. The dynamic modulus database to be developed from this project will yield necessary information for the NCDOT to design asphalt pavements with lime-modified mixtures using the new AASHTO pavement design guide.

Typical Dynamic Moduli for North Carolina Asphalt Concrete Mixes
Y. R. Kim
NC Department of Transportation
07/02 to 06/04
The dynamic modulus of asphalt concrete will be used as the key parameter in the 2002 AASHTO Design Guide as well as in the Superpave simple performance test protocol that complements the volumetric mix design. The release of the new AASHTO pavement design guide in 2002 makes it urgent to obtain dynamic moduli values of typical asphalt mixes used in North Carolina. The objective of this proposal is to develop a database of dynamic moduli values and their variability for asphalt mixes used in North Carolina. In addition to dynamic modulus testing of the representative mixes, surrogate methods will be evaluated, including the impact resonance method and Witczak's predictive equation.

Impact of Price Reductions on the Long-Term Pavement Performance of HMA Mixes in North Carolina
Y. R. Kim
NC Department of Transportation
07/01 to 06/03
Article 105-3 of the North Carolina Department of Transportation (NCDOT) Standard Specifications for Road and Structures provides guidance on price adjustments for hot mix asphalt pavements that are not within reasonably close conformity with the specifications but for which the work is to be accepted and remain in place. The primary objective of the proposed research herein is to determine whether price reduction under the provisions of Article 105-3 is adequate. The research objective will be accomplished by conducting both field and laboratory analyses of deficient pavements and specification pavements with similar structures and traffic history. The types of deficiency to be addressed in this research include asphalt content and in-situ density. Both fatigue and rutting performance will be evaluated.

Development of Specification Testing to Promote Fracture Fatigue Resistance and to Optimize Microdamage Healing
Y.R. Kim and M.N. Guddati
Texas AandM Research Foundation/Western Research Institute/FHWA
07/01/99 to 06/30/03
The ultimate goal of this project is "to be able to classify/specify/improve asphalts by their healing rates and efficiencies using chemical data that can be acquired more rapidly than by mechanical methods." To accomplish this goal, the viscoelastic, continuum damage model developed by the PI will be tied to the micromechanical properties of component materials using DM2, a discrete element code developed by the Co-PI. Various test methods will be explored for binder specification testing using the viscoelastic, continuum damage formulation and DM2 simulation with an objective to promote fatigue resistance and to optimize the microdamage healing potential.

A Unified Approach to Predicting Long Term Performance of Asphalt-Aggregate Mixtures
Y.R. Kim, R.H. Borden and Y. Horie
National Science Foundation
09/98 to 12/02
The research objective is to develop test methods and models for predicting long term performance of asphalt concrete that can account for viscoelasticity, damage, volumetric/deviatoric coupling, temperature, and aging. The objective will be accomplished by applying the elastic-viscoelastic correspondence principle and the continuum damage theory. The constitutive model will be incorporated into the ABAQUS finite element code, and used to predict the response and performance of laboratory pavements loaded by the Model Mobile Load Simulator. Nondestructive surface wave tests will be performed to determine the change in material properties due to fatigue damage growth.

Development of Visco-Elasto-Plastic Continuum Damage Model for Asphalt-Aggregate Mixtures
Y.R. Kim
Arizona State University
03/00 to 08/03
This project is a subcontract from Arizona State University as a part of the NCHRP 9-19 project "Superpave Support and Performance Models Management." The objective of this project is to develop test protocols and models for characterization of asphalt concrete that are needed for structural design and mix design. The NCSU research team will perform experimental/analytical research to evaluate elastic, viscoelastic, viscoplastic responses of asphalt concrete under varying conditions and to develop a constitutive model that can be implemented in finite element analysis for performance prediction of asphalt pavements.

In-Vehicle Energy and Emissions Information System
H. C. Frey and N. M. Rouphail
National Science Foundation
01/03 to 12/05
The key objectives of this research project are to: (1) develop a micro-scale predictor of energy use and emissions that is deployable at the individual vehicle level in real-time; (2) identify, compare and evaluate alternate energy use and emissions sampling/reporting schemes that are appropriate at the vehicle and network levels; (3) Develop and test a prototype In-Vehicle Energy and Emissions Information System (IVEEIS); and (4) formulate and assess the utility of IVEEIS in developing transportation design and control measures aimed at energy and emission management policies.

Eisenhower Graduate Fellowship
N. M. Rouphail (Tori Rhoulac, Fellow)
Federal High Administration (FHWA)
09/01 to 08/04
The Dwight David Eisenhower Transportation Fellowship Program was created to attract, enhance, and retain the Nation's brightest minds in the transportation research and engineering professions. The recipient will be conducting research on the application of Intelligent Transportation Systems and related transportation engineering concepts and technologies to multi-modal school transportation problems.

Traditional Neighborhood Development Trip Generation Study
J. R. Stone and A. Khattak (UNC-CH)
NC Department of Transportation
07/02 to 12/03
This project focuses on Southern Village, a Chapel Hill high-density development that combines residential, business and office land uses. Having trip origins and destinations close to one another enhances walking, biking and transit transportation, and, thereby, reduces the need for automobile travel. Evaluation of behavioral travel surveys and traffic data for Southern Village versus a conventional suburban development tests this concept. Findings will affect how NCDOT and other agencies test regional land use scenarios such as "smart growth" and how professionals conduct traffic impact analyses for mixed use development.

North Carolina Forecasts for Truck Traffic
J.R. Stone
North Carolina Department of Transportation
07/03 to 12/04
Estimates of truck traffic are critical parameters in designing and maintaining highway pavement and structures. National databases suggest that trucks are becoming an increasingly larger proportion of traffic. Anecdotal reports suggest that North Carolina truck traffic is increasing in excess of national averages. Consequently designers apply generous adjustments for forecast truck traffic. However, over estimates lead to over design and unnecessary construction cost. This project helps resolve these issues through improved data collection, display and analysis techniques.

Materials Characterization and Performance Properties of Superpave Mixtures
A. A. Tayebali
NC Department of Transportation (NCDOT)
01/01 to 12/03
A critical step in the implementation of mechanistic/empirical design procedure is the development of strain-fatigue life relationship. In this investigation, materials characteristics and fatigue performance of few asphalt mixes currently used in North Carolina will be evaluated. The study of these mixes will initiate the development of better understanding of the capacity of Superpave mixes to resist fatigue distress by providing information that can be used to identify deficiencies and make necessary improvements in the current NCDOT design procedures.

Effect of Percentage Baghouse Fines on the Amount and Type of Antistripping Agent Required to Control Moisture Sensitivity
A. A. Tayebali
NC Department of Transportation
07/01 to 03/03
This research proposes to conduct a laboratory study of moisture sensitivity of asphalt mixes containing controlled percentages of baghouse fines in the amount of 0, 4, and 8-percent. Antistripping agent(s) selected in consultation with NCDOT will be used to determine their effectiveness in mitigating moisture damage. The study outcome should result in clear recommendations regarding maximum level of baghouse fines, the appropriate type and amount of antistripping agent, and any significant performance issues that are uncovered by the research team.

A Mechanistic Approach to Evaluate Contribution of Prime and Tack Coats in Composite Asphalt Concrete Pavements
A. A. Tayebali and S. Rahman
NC Department of Transportation (NCDOT)
07/00 to 06/03
The importance of proper AC layer interface bonding cannot be overemphasized for good performance of AC pavements. A strong bonding between layers is critical to dissipate shear stresses into the entire pavement structure. On the other hand, lack of bonding may cause slippage phenomenon and activate distress mechanisms that will rapidly lead to total failure of the pavement. The objective of this study is to evaluate the effects of different prime and tack coats on the bond strength in relation to the thickness of the asphalt concrete layer. In particular, the distribution and dissipation of shear stresses under traffic loading and how they effect the interlayer bonding will be studied. Based on the results of the study, correlation will be developed between delamination parameters and stress-strain-displacement field.

Shear and Axial Repeated Load Behavior of Asphalt Concrete Mix Designed Using Marshall and Superpave Mix Design Procedure
A. A. Tayebali
Nichols Consulting Engineers
07/01 to 12/02
The objective of this study was to evaluate three mixes using Keystone, Wells, and Zolezzi aggregates from Nevada designed using the Superpave and Marshall mix design procedures. Repeated axial and shear tests were conducted using the Simple Shear Test machine (SST). Axial and shear test results indicate that in general, there was no difference in the behavior of the mixes designed using the Superpave or the Marshall procedure. In some cases, the behavior of the Marshall designed mix was found to be better than the Superpave mixes.

Standard Test Method for Determining Effectiveness of Asphalt Removing Solvents
A. A. Tayebali
NC Department of Transportation (NCDOT)
07/01 to 08/02
A large number of different environmentally friendly, safe and biodegradable asphalt removing solvents are available in the market. This study, sponsored by NCDOT, outlines the development of a procedure used to evaluate the cleaning efficacy of various solvents. The goal was to develop a standardized procedure that would yield quantitative and repeatable results. After evaluating various alternatives like metal and glass plates, ceramic tiles, and aluminum foils, the standard aluminum dish (from Fisher brand) was used for the study. The results obtained are consistent and repeatable, with coefficient of variation less than 10% for most solvents. Further, this study provides an outline for cost effective analysis of solvents used. This study found that in comparison to diesel fuel, Citrus-Sol-PlusE was the best performing and most cost effective asphalt removing solvent.

CAREER: System-wide Traffic Condition Monitoring and State Estimation for Intelligent Transportation Systems
B.M. Williams
National Science Foundation
06/02 to 05/07
This project will provide an integrated research and education framework for system-wide traffic condition monitoring and state estimation for intelligent transportation systems (ITS). Research activities will include: development of a system-wide ITS traffic condition monitoring and forecasting framework, seasonal ARIMA based Kalman filtering forecasts, continuum traffic flow theory based one-step forecasts, and continuum theory-based incident detection, missing data estimation, and shock wave propagation prediction. Educational activities will include undergraduate course development and enhancement, development of a new traffic flow theory courses to support ITS research, involvement of undergraduates in ongoing ITS research activities, and active recruitment of underrepresented student groups.